1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device. More particularly, the present invention relates to a liquid crystal display (LCD) device and a method for manufacturing the same, capable of maintaining a cell gap and preventing press defects caused by application of external pressure via the use of ball spacers.
2. Discussion of the Related Art
With the progress of a information-dependent society, the demand for various display devices has increased. To meet such demands, efforts have recently been made to research flat panel display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), electro-luminescent displays (ELDs) and vacuum fluorescent displays (VFDs). Some types of such flat panel displays are being practically applied to various appliances for display purposes.
Of these, LCDs are currently most widely used as substitutes for cathode ray tubes (CRTs) in association with mobile image display devices because LCDs offer advantages such as superior picture quality, lightweight, slimness, and low power consumption. Various applications of LCDs are being developed in association with not only mobile image display devices such as monitors of notebook computers, but also monitors of TVs to receive and display broadcast signals, and monitors of laptop computers.
Successful application of such LCDs to diverse image display devices depends on whether or not the LCDs can realize desired high picture quality including high resolution, high brightness, large display area, and the like, while maintaining desired characteristics of lightweight, slimness and low power consumption.
Hereinafter, the structure of a related art LCD device will be described with reference to the attached drawings.
FIG. 1 is a plan view illustrating a related art LCD provided with a column spacer.
As shown in FIG. 1, a related art LCD array region comprises gate lines 4 and data lines (not shown) that cross each other to define pixel regions, thin film transistors (TFT) each formed at a crossing between the gate lines 4 and the data lines, and pixel electrodes 6 formed in each of the pixel regions. The array region further comprises column spacers 20 uniformly spaced apart from one another, to maintain a cell gap. In FIG. 1, column spacers 20 are arranged at respective pixels, each of which includes three sub-pixels, i.e., R, G and B sub-pixels.
As shown in FIG. 1, each column spacer 20 is arranged in a region provided above the gate line 4. That is, the gate line 4 is arranged on a first substrate 1, a gate insulating film 15 is arranged over the entire surface of the first substrate 1 including the gate line 4, and a passivation film 16 is arranged on the gate insulating film 15.
Meanwhile, a second substrate 2 comprises a black matrix layer 7 to shield non-pixel regions (portions where gate lines, data lines and thin film transistors are formed) other than the pixel regions. In addition, R, G and B color filter layers are formed at respective pixel regions on the second substrate 2 including the black matrix layer 7, and a common electrode 14 is arranged over the entire surface of the second substrate 2 including the color filter layers 8.
The column spacers 20 are formed on portions of the common electrode 14 corresponding to the gate lines 4. Accordingly, the first and second substrates 1 and 2 are joined together such that the column spacers 20 are arranged on the gate lines 4.
The column spacers 20 are formed in an array process of the first substrate 1 or the second substrate 2. The column spacers 20 are fixedly formed in the form of columns with a certain height on the predetermined substrate.
The column spacers 20 are fixed in specific positions and thus do not move, when liquid crystals are dropped to form a liquid crystal layer. Advantageously, the column spacers do not inhibit the liquid crystals from flowing. However, the column spacers have a large area in contact with the corresponding substrate, thus disadvantageously causing display defects, e.g., touch defects.
The LCDs including afore-mentioned column spacers suffer from the following problems.
A region, where the liquid crystal panel of the related art column spacers-comprising LCDs is touched in a certain direction by hand or other objects, is stained. This stain is formed upon touch and is thus referred to as a “touch stain”. As such, the stain is observed on the screen and thus is also called a “touch defect”. Such a touch defect is considered to be attributed to the high frictional force which is caused by the large contact area between the column spacer and the corresponding substrate, as compared to related art ball spacer structures. That is, because column spacers have a large area in contact with the corresponding substrate, as compared, for example, to ball spacers, after upper and lower substrates shift towards each other upon touching, they take a long time to return to an original state and stains thus remain until they completely return to the original state.
Accordingly, efforts have been made to use ball spacers in liquid crystal panels. In these cases, the ball spacers move and deviate from their original positions during fabrication and use due to their mobility. Thus, causing other problems. Research is being conducted on solving these problems.